Hey, H.-- I know I'm responding later than everyone else, but I saved your question because I've been thinking of you for two days and I hope you are less discouraged than you were when you asked your question.
I am a La Leche League Leader in Utah, and I highly recommend you contact your local Leader to get accurate, personal breastfeeding counseling absolutely free. I don't know Colorado geography very well, but there are dozens of Leaders there. You could find the ones closest to you by clicking on "resources" and "find a local group" at www.llli.org. We are required to stay current on our information and our accreditation (while not medical like an IBCLC certification) is very thorough.
Since milk production is all supply and demand, you may be shooting yourself in the foot (breast?) by offering a bottle of artificial baby milk. It's good to remember swallowing is a reflex, and baby will continue to swallow even if he's technically "full," just because a bottle continues to drip fluid into his mouth.
You sound like an intuitive mom--you see he is fussy. Consider that a change in your supply may not be the sole reason for an increase in fussiness. He could be teething, dealing with an upper respiatory infection that makes his stuffy and crabby, he could be overstimulated and need to be rocked to sleep instead of nursed. It's highly likely he is hitting a growth spurt, too. All of this means that short, frequent feedings may meet his needs better than his previous marathon nursing sessions. Frequent nursing will both stimulate your breasts to increase supply and allow him to get the high-fat hindmilk that will keep him satisfied longer.
It's important NOT to judge your supply based on how much you can pump. The best pump in the world has nothing on a well-latched baby! Watching his output of urine/stool is more reliable than measuring quantity of milk pumped. Since you are concerned about supply, consider using breast compression techniques while you pump: you just hold your hand in a "c" shape and gently compress and hold your breast while you pump or nurse for the count of 15 to 10. Then, shift your hand to another part of your breast and compress again. This allows your baby or pump to effectively drain (and thus, stimulate) all the milk ducts. It also helps many babies maintain interest, since they often get a gush of milk when you shift your hold, since your compression temporarily blocked some ducts. Other rules of thumb (breast?) when using a pump to increase supply is to use a double electric pump, since studies show moms who pump both breasts at once increase production more effectively, AND pump for two minutes after when you see the last drop of milk come out.
Human milk production takes about 24 to 48 hours to adjust to an increased or decreased demand. This means the most effective way to increase your supply is to nurse often. Consider having what many moms call a "milk day," and letting other obligations wait while you make nursing often your primary focus for a day or two. This can allow your supply to catch up with his demand.
Even though he sleeps for such a long stretch, keeping him nearby when he's sleeping can also help your supply. Studies show prolactin levels peak in the very early morning hours, making that an ideal time to pump or nurse. Many moms worried about supply take their babies to bed with them or just nap with them so they can both get extra rest and the extra homornal triggers to produce more milk.
Fenugreek, blessed thistle and domperidone are all useful for many moms who wish to increase their supply. Fenugreek will make you sweat and urine smell like maple syrup. It also messes with blood sugar, so don't use it if you are diabetic. If you wish to use it, or use other herbal treatments, consider taking them in capsule form, as any sort of tea or beverage is hard to measure accurately and you can never be sure how mch you're really getting. Sage and any contraceptive containing estrogen are known to decrease milk supply, and antihistimines can also compromise your supply, since they work by drying up excess body fluds, so use these with caution.
Solid food should mainly be for experience with texture and fun, not real nutrition at this age. Your milk changes flavors, so he does not really need solid food for the purpose of tasting new flavors. Offer solids after nursing when you are both relaxed, and avoid using the spoon to supress any remaining tongue-thrust reflex he may still have. The American Academy of Pedatrics recommends babies breastfeed exclusively for at least the first six months (nice work, mama!) and then continue until at least one year of age, and thereafter as long as is mutually desired by mom and baby.
You received so much well-meaning advice, and much of it was conflicting. While moms were so kind to remind you that not breastfeeding would not be the end of the world, I suggest you remember that *their* experience does not necessarily have to be *your* experience, if you'd like something different. You are the expert on your child, since you are his mother. You decide what your mothering and breastfeeding experience will be like, if this setback is a real brick wall or just a speed bump to get over. Breastfeeding is very much a confidence game, and I offer you my sincere vote of confidence. I hope some of this information is useful to you, or at least reassuring. Hang in there!